Method and welding system for welding internal corners of u-ribs of a steel bridge in service

Abstract

The application provides a method for welding inner corners of U-rib of a steel structure bridge in service, both ends of the U-rib are respectively provided with a partition plate, and the method comprises the following steps: S1, opening a welding construction section: opening a construction window for welding on the U-rib in service, the opening position of the construction window is located between two partition plates on both sides of a welding seam of the U-rib, and is located on both sides of a butt welding seam of a plate unit to which the U-rib is welded, and each adjacent two construction windows are a welding construction section; S2, cutting the partition plates on both sides of the construction window and taking out the cut partition plates; S3, polishing the cutting boundary of the plate unit and the U-rib in a construction section, and cleaning the inside of the U-rib of the welding construction section; S4, upwelding the inner corner of the U-rib in the welding construction section in step S3; and S5, restoring welding of the U-rib in the welding construction section in step S4.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and specifically to a method and welding system for welding the inner corner of the U-rib of an in-service steel structure bridge. Background Technology

[0002] Longitudinal orthogonal steel structure bridges are currently the main structural form for long-span, heavy-duty welded steel structure bridges, and U-ribs are a standard component of traditional orthogonal steel structure bridges. In the early days, many longitudinal U-rib orthogonal steel structure bridges built in my country, due to limitations in theory and technology at the time, did not have their inner corners of the U-rib plates welded; only the outer corners were welded. During later service, fatigue loads caused cracks to develop at the inner corners, creating safety hazards for the bridges in service.

[0003] Currently, welding repair methods for bridge U-ribs only address cracks that have extended to the outer side of the U-rib and the surface of the bridge top plate (referred to as plate units in this article). These methods involve cleaning and welding to repair the cracks. The inner corners of the U-rib cannot be welded, failing to fundamentally alter the internal geometry and stress distribution. This results in frequent maintenance of in-service bridges and makes it difficult to eliminate safety hazards. Due to the narrow and elongated internal space of the U-rib, current technology cannot weld the inner corners of the U-ribs in in-service bridges. Furthermore, it is difficult to stop the bridge from operation for repairs during its service life, which is highly detrimental to the repair of the inner corners of the bridge's U-ribs. Summary of the Invention

[0004] This invention provides a method and welding system for welding the inner corners of U-ribs in in-service steel structure bridges, which can perform overhead welding to reinforce and repair the inner corners of U-ribs in bridges where the inner corners of the U-ribs were not welded in the early stages.

[0005] The first aspect of the present invention provides a method for welding the inner corner of a U-rib of an in-service steel structure bridge, wherein the U-rib is provided with partitions at both ends, characterized in that the method includes the following steps:

[0006] S1. Establishing a welding construction section: A construction window for welding is opened on the in-service U-rib. The construction window is located between two partitions on both sides of the weld seam of the U-rib and on both sides of the butt weld seam of the plate unit on which the U-rib is welded. Each pair of adjacent construction windows constitutes a welding construction section.

[0007] S2. Cut the partitions on both sides of the construction window and remove the cut partitions;

[0008] S3. Grind the cutting boundaries of the plate unit and U-rib within a construction section, and clean the interior of the U-rib in the welding construction section.

[0009] S4, upwelding the inner corner of the U-rib in the welding construction section in step S3; and

[0010] S5, recovery welding the U-rib in the welding construction section in step S4.

[0011] Preferably, the longitudinal length of the construction window is 50-100mm less than the distance between the two partitions, and the distance from the construction window to the lower surface of the plate unit is greater than 80mm, and wherein the step S1 comprises the following steps:

[0012] S1-1, marking the U-rib according to the size and position of the construction window; and

[0013] S1-2, cutting along the line marked in step S1-1, and removing the cut U-rib part to form a construction window.

[0014] Preferably, the step S3 of grinding the plate unit and U-rib comprises:

[0015] S3-1, grinding the cut between the removed partition and the plate unit and the U-rib;

[0016] S3-2, grinding the excess height of the butt weld of the plate unit and the metal backing plate in the U-rib; and

[0017] S3-3, grinding the area to be welded in the U-rib.

[0018] Preferably, the step S4 comprises the following steps:

[0019] S4-1, placing an upwelding vehicle for upwelding the inner corner of the U-rib on a lifting platform, which is arranged on the ground below one construction window of the welding construction section;

[0020] S4-2, arranging a temporary support at another construction window of the welding construction section;

[0021] S4-3, lifting the lifting platform to a height such that the upwelding vehicle can smoothly enter the interior of the U-rib;

[0022] S4-4, starting the upwelding vehicle to upweld the inner corner of the U-rib in the longitudinal direction of the U-rib inside the U-rib; and

[0023] S4-5, after welding, running the upwelding vehicle to the lifting platform again, and lowering the lifting platform to the initial height, and taking out the upwelding vehicle.

[0024] Preferably, the overhead welding vehicle is provided with a welding gun, which includes a welding gun nozzle and a conducting nozzle, and the distance between the conducting nozzle and the welding gun nozzle is 5-15 mm.

[0025] Preferably, the welding speed of the overhead welding vehicle and the arc swing frequency of the welding gun satisfy the following formula:

[0026] v=KfB

[0027] wherein v represents the welding speed; K represents the overlap coefficient; f represents the swing frequency; B represents the weld width when the linear welding speed is ; and w represents the swing amplitude.

[0028] Preferably, the step S5 includes the following steps:

[0029] S5-1, sealing the partition plates in the U-rib, and sealing the construction window;

[0030] S5-2, post-processing the sealing of the construction window.

[0031] Preferably, the step S5-1 further includes, when the welding operation of the bridge is not completed, sealing the partition plates at both ends of one of the construction windows in one of the welding construction sections, sealing the construction window, and opening a new construction window at the other end of the other U-rib corresponding to the other construction window, and taking the other construction window and the newly opened construction window as the next welding construction section.

[0032] Preferably, the method further includes: S6, painting the outer surface of the sealing of the construction window.

[0033] According to the second aspect of the present application, a welding system is provided for implementing the method of welding the internal corner of the U-rib of the in-service steel structure bridge according to any one of claims 1-9, and the welding system includes a lifting platform, a temporary support and an overhead welding vehicle.

[0034] The lifting platform is arranged on the ground below one of the construction windows of the welding construction section, and is used to send the overhead welding vehicle into the U-rib through the construction window.

[0035] The temporary support is used to support the driving of the overhead welding vehicle, and the temporary support is arranged at the construction window below which no lifting platform is arranged.

[0036] Preferably, the temporary support is a detachable track.

[0037] Advantages:

[0038] The application provides a method and a welding system for welding the inner corner of an in-service U rib.

[0039] In addition, the method for welding the inner corner of the in-service U rib of the application uses the cooperation of the lifting platform and the temporary support to make the manual operation more convenient, avoids the harm to the operator, saves time and effort, and does not need to stop the use of the bridge, so that the U rib can be repaired under the normal operation of the bridge, without the complex operation process such as disassembly and assembly of the U rib, and the economic benefit maximization is realized. In combination with the above-mentioned specific multiple construction windows, the continuous operation of the U rib inner corner welding can be realized, and the equipment operation does not need to be stopped during the welding process, and the continuous operation can be realized in the continuous welding construction section. Further, when multiple sets of welding operation equipment are provided, multiple welding construction sections can be simultaneously constructed, which greatly improves the construction efficiency and safety. The in-service U rib without inner welding can be reinforced and welded for repair under the condition that the bridge is not interrupted, which has significant economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A schematic view of the construction window opened on the U rib during the welding construction of the method for welding the inner corner of the in-service U rib according to the application;

[0041] Figure 2 A schematic view of the construction window opened on the U rib during the welding construction of the method for welding the inner corner of the in-service U rib according to the application; Figure 1 A cross-sectional enlarged schematic view of the middle section A-A;

[0042] Figure 3 A cross-sectional enlarged schematic view of the middle section B-B; Figure 1 A cross-sectional enlarged schematic view of the middle section B-B;

[0043] Figure 4 A schematic view of the lifting platform and the temporary support in the welding system during the welding construction of the method for welding the inner corner of the in-service U rib according to the application;

[0044] Figure 5 A schematic view of the lifting platform and the temporary support in the welding system during the welding construction of the method for welding the inner corner of the in-service U rib according to the application;

[0045] Figure 6 A schematic view of the lifting platform and the temporary support in the welding system during the welding construction of the method for welding the inner corner of the in-service U rib according to the application;Figure 5 An enlarged sectional view of the middle section C-C;

[0046] Figure 7 A bridge U rib after completion of welding and welding of a construction window to the U rib at the time of welding construction for the method of welding an inner corner of an in-service U rib according to the present application;

[0047] Figure 8 A schematic view from the longitudinal front of the bridge U rib after completion of welding and welding of a construction window to the U rib at the time of welding construction for the method of welding an inner corner of an in-service U rib according to the present application;

[0048] Figure 9 A schematic view of the welding position of the overhead welding vehicle according to the present application at the time of construction. Figure 7 An enlarged sectional view of the middle sections D-D and E-E and Figure 8 An enlarged sectional view of the middle section G-G;

[0049] Figure 10 A schematic view of the welding position of the overhead welding vehicle according to the present application at the time of construction.

[0050] It is to be understood that the drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the application. Specific design features, e.g., particular dimensions, orientations, locations, and shapes, of the present application as herein disclosed will be determined in part by the particular intended application and use environment.

[0051] In the drawings, like reference numerals refer to like parts throughout the various drawings, in which several views of the application are presented. DETAILED DESCRIPTION

[0052] Reference will now be made in detail to various embodiments of the application, examples of which are illustrated in the accompanying drawings and described below. While the application will be described in conjunction with the exemplary embodiments, it will be understood that they are not intended to limit the application to those exemplary embodiments. On the contrary, the application is intended to cover all alternatives, modifications, equivalents and other embodiments, including those pertaining to the spirit and scope of the application as described by the appended claims.

[0053] Hereinafter, exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. The specific structures and functions described in the exemplary embodiments of the present application are merely for illustrative purposes. Embodiments according to the concept of the present application can be implemented in various forms and it is understood that they should not be interpreted as being limited to the exemplary embodiments described in the exemplary embodiments, but include all modifications, equivalents, or alternatives included in the spirit and scope of the present application.

[0054] Throughout this specification, the use of "professional terms" is used only to describe various exemplary embodiments and is not intended to be limiting. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0055] It should be noted that the "longitudinal" and "transverse" mentioned in the present application, without special instructions, "longitudinal" generally refers to the length direction of the U rib, and correspondingly, "transverse" refers to the direction along the width of the U rib. In addition, it should be understood that the directional words used in the present application, such as "upper", "lower", "left", "right", "front", "back", "inner", "outer", "horizontal", "vertical", "perpendicular to", and "intersecting", and the like, unless otherwise specifically stated, are described with reference to the drawings, and the description is not restrictive but illustrative.

[0056] It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element, or intervening elements can be present therebetween. Conversely, it will be understood that when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present. Other expressions that describe the relationship between elements, such as "between", "directly between", "adjacent to", or "directly adjacent to", should be interpreted in the same way.

[0057] Throughout this document, unless otherwise specifically stated, as shown in Figures 1 to 3 The U rib mentioned in the present application can be generally used in the orthogonal steel structure bridge, and of course, in some specific cases, it can also be used in other systems that need to use the U rib as a standard fixing element, such as large cement reinforced platforms. And the U rib mentioned in the present application has been welded to the plate unit 10 by corner welding during construction (as shown in Figure 3 Specifically, each two plate units 10 have butt welds 11 due to the welding connection, similarly, each two connected U ribs 20 also have welds 22 due to the welding connection, the U rib has a partition 30 at the head and tail ends, and the inner surface of the U rib 20 is provided with a metal backing plate 40 (the metal backing plate is as shown in Figure 8 When the U rib is welded (welding the U rib plate instead of the inner and outer corner welding), the metal backing plate 40 needs to be welded first in the case of being provided with the metal backing plate 40, so as to fix the U rib plate.

[0058] In addition, the "in service" referred to herein, unless otherwise stated, refers to the case in the normal use stage, that is, the U rib is in the bridge or other system structure that is being used.

[0059] As mentioned above, in Figures 1 to 3 , the inner corner of the U rib 20 has not been welded, so it can be seen from Figure 2 and Figure 3 that only the outer corner W between the U rib 20 and the plate unit 10 is welded.

[0060] According to the first aspect of the present application, a method for welding the inner corner of the in-service U rib is provided, which adopts a segmented welding method so that multiple segments can be constructed simultaneously, thereby improving work efficiency.

[0061] Specifically, the method provided by the present application comprises the following steps: opening a welding construction segment: opening a construction window S1 for welding on the in-service U rib 20, as shown in Figure 1 The opening position of the construction window 21 is between the two partitions 30 on both sides of the welding seam 22 of the U rib 20, and is located on both sides of the butt welding seam 11 of the plate unit 10 to which the U rib 20 is welded, in other words, the construction window 21 is opened at the position where two U ribs 20 are connected end to end, i.e. the leading end of one U rib 20 and the trailing end of the U rib 20 connected to the leading end. In this regard, there is one welding construction segment P between each adjacent two construction windows 21, according to the attached Figure 1 It can be seen that the part enclosed by the dashed line is one welding construction segment P. During the execution of the segmented welding method, each welding construction segment P is welded respectively. In each welding construction segment P, the inclined welding seam of the previous welding construction segment P and the inclined welding seam of the next welding construction segment P are connected end to end.

[0062] Here, it should be noted that the above-mentioned construction window 21 is opened on the U rib to be repaired to form the welding construction segment P, but if the construction window 21 is opened too much, it will affect the rigidity and strength of the bridge, therefore, the construction window 21 needs to be weighed according to the actual need for welding the mechanical structure and the construction period of the in-service bridge. However, in the absence of special instructions in this article, multiple construction windows are usually not opened continuously, and a certain number of construction windows are usually opened every few U ribs, so that construction cannot be carried out simultaneously in adjacent segments, which can ensure the rigidity of the bridge plate unit and will not affect the use of the bridge.

[0063] The opening position of the above-mentioned construction window is between the two partitions 30 on both sides of the welding seam 22 of the U rib 20, and is located on both sides of the butt welding seam 11 of the plate unit 10 to which the U rib 20 is welded. By opening such a construction window, it can be extended to the U ribs at both ends of the construction window from the construction window no matter left or right, so that the overhead welding car can run back and forth based on the two construction windows during subsequent welding.

[0064] In one embodiment of this application, the longitudinal length of the construction window 21 is less than the distance between the two partitions 30 by 50-100mm, thereby ensuring that the construction window is located between the two partitions 30, which ensures that the subsequent cutting of the partitions 30 can be carried out smoothly and the partitions 30 can be removed smoothly. Furthermore, the distance from the top of the construction window 21 to the lower surface of the plate unit 10 is greater than 80mm. Figure 1 As shown, distance a is the longitudinal length of welding window 21, and distance b is the distance from the top of construction window 21 to the lower surface of plate unit 10. In other words, the height above the side plate of U-rib 20 needs to be greater than 80mm. This ensures that the plate unit of the bridge can still have the necessary rigidity after construction window 21 is removed. In addition, the height above can provide some guidance for the subsequent overhead welding car to enter the overhead welding car of U-rib. Furthermore, this distance keeps the welding position away from the bridge deck, avoiding the impact of subsequent welding on the bridge deck pavement material.

[0065] The specific method for creating the construction window 21 for welding includes the following steps: S1-1, the U-rib is marked with lines according to the size and position of the construction window. The marking method can use commonly available marking equipment, and this application does not impose any special restrictions on it; then, the U-rib portion is cut along the lines marked in step S1-1 and removed to form the construction window 21. The removed U-rib portion is the construction window plate (not shown). After the inner corner overhead welding is completed, the construction window plate needs to be re-welded to the U-rib when restoring the U-rib. The specific method is detailed below.

[0066] In some embodiments of this application, after removing the cut U-rib portion, the cut boundary of the U-rib needs to be polished to remove the cutting burrs, so as to avoid subsequent cuts causing injury to operators and equipment by scratching.

[0067] After opening the aforementioned construction window 21, the partition plate 30 inside the U-rib 20 is cut and removed within a construction section (S2). During cutting, the partition plate 30 can be cut along the weld seams at its four corners. It is important to ensure that the cuts do not damage the bridge's plate unit 10, the sides and bottom of the U-rib 20, or the metal plates on the sides and bottom of the U-rib 20. Cutting and removing the partition plate 30 allows subsequent cleaning equipment and the overhead welding machine 51 to enter the interior of the U-rib for cleaning and welding.

[0068] After cutting the partition plate 30 and taking out the cut partition plate, the cutting boundary of the plate unit 10 and the U rib 20 is polished, and the inside of the U rib 20 of the welding construction section P is cleaned S3. Specifically, the polishing of the plate unit and the U rib 20 in step S3 includes polishing the cut of the removed partition plate 30 and the plate unit 10 and the U rib 20 S3-1, and the polishing is preferably in the form of carbon arc gouging or grinding with a grinding wheel, an angle grinder, etc., so that the cut of the plate unit and the U rib 20 of the cut partition plate 30 is gouged or polished flat, so that the protruding height of the cut is less than 1 mm and is not recessed.

[0069] Subsequently, the excess height of the butt weld of the plate unit 10 and the metal backing plate 40 in the U rib 20 are polished S3-2, and in some embodiments of the present application, the polishing can be in the form of carbon arc gouging, grinding with a grinding wheel, or polishing with an angle grinder, etc., and after polishing, the excess height of the butt weld is ensured to be not higher than 2 mm, and cannot be inwardly recessed (i.e. the excess height protrudes 0-2 mm from the lower surface of the plate unit 10). This facilitates the smooth passage of subsequent cleaning equipment and overhead welding equipment without being jammed.

[0070] Finally, the area to be welded in the U rib 20 is polished S3-3 (i.e. the inside corners of the U rib 20 are polished), and in some embodiments of the present application, the polishing of the inside corners can be performed by a specially designed steel wire wheel polishing vehicle, which enters from an opened construction window 21 and polishes the rust on the area to be welded by a steel wire wheel polishing element. This process is different from the polishing processes of steps S3-1 and S3-2, and the polishing of the inside corners is mainly to polish the inside corners to remove the oxides and other impurities thereon, so that the subsequent welding work can be carried out smoothly, and the solder will not be welded on the oxides or impurities, which will cause the solder to fall off during future use. In some embodiments, the range of rust removal polishing is within 15 mm on both sides of the inside corner line of the U rib 20 and the plate unit 10.

[0071] After polishing is completed, a large amount of cutting debris, dust, rust and other impurities will be generated inside the U rib 20, which is not conducive to the travel and maintenance of the overhead welding vehicle 51 in the later stage, and therefore, the inside of the U rib 20 of the welding construction section P needs to be cleaned. In some embodiments of the present application, a specially designed obstacle removal vehicle (not shown) is used to enter from one construction window 21 of each welding construction section P, and all the obstacles in the U rib 20 that hinder the operation of the overhead welding vehicle 51 are pushed to the other construction window 21 so as to be taken out.

[0072] After cleaning, the impurities in the U rib 20 that hinder the travel of the equipment have been removed, and at this time, the U rib 20 can be overhead welded, and in some embodiments of the present application, the overhead welding vehicle 51 is used to perform overhead welding S4-1, and the welding is performed from the inside corner of the U rib 20 to the outside corner of the U rib 20. Figure 4 and Figure 5As shown, the inner corner of the U-rib in the welding construction section P in step S3 is overhead welded S4. The specific welding steps include: placing an overhead welding vehicle 51 for overhead welding of the inner corner of the U-rib on a lifting platform 52 arranged on the ground below one of the construction windows 21 S4-1.

[0073] In some embodiments, the lifting platform 52 is arranged on the ground corresponding to the construction window, and a rack is arranged on the ground, a lifting rod is arranged above the rack, the lifting platform is located at the top end of the lifting rod, the lifting platform is moved in the vertical direction by the lifting rod, and wheels are arranged below the rack to facilitate movement of the rack on the ground, so that the rack can be moved to each construction window. The lifting platform 52 can be provided with buckles (not shown) to prevent the overhead welding vehicle 51 from falling due to shaking during subsequent lifting. The specific form of the buckle is not particularly limited in the present application, as long as the overhead welding vehicle 51 does not fall during lifting and does not hinder the travel of the overhead welding vehicle 51 when it reaches the welding position.

[0074] A temporary support 63 is arranged at another construction window of the welding construction section S4-2, so that the overhead welding vehicle can pass through. The temporary support can be a detachable track, a detachable platform, etc., which functions to support the overhead welding vehicle when it reaches the construction window, so that the overhead welding vehicle can smoothly pass through the construction window without falling, and can ensure that the overhead welding vehicle always travels in the longitudinal direction of the U-rib. Most preferably, the temporary support is in the form of a detachable track.

[0075] After the overhead welding vehicle 51, the lifting platform 52 and the temporary support 53 are arranged, the lifting platform 52 is raised to a height at which the overhead welding vehicle 51 can smoothly enter the inside of the U-rib 20 S4-3, the overhead welding vehicle 51 is started, and the overhead welding vehicle 51 is used to overhead weld the inner corner of the U-rib 20 in the longitudinal direction of the U-rib S4-4.

[0076] In some embodiments of the present application, the overhead welding vehicle 51 preferably uses carbon dioxide gas shielded arc welding or MAG welding. In addition, the overhead welding vehicle 51 is provided with a welding gun 514, as shown in Figure 6As shown, the number of welding torches can be two, which are respectively used to weld the two inner corners of the U-rib 20, and during the overhead welding, the electric arc of the welding torches swings, and the swing frequency and amplitude will be described in detail below. In some embodiments of the present application, when the overhead welding vehicle 51 is provided with two welding torches, after entering the construction window 21, the overhead welding vehicle 51 does not weld during the process of traveling to another construction window 21, and directly travels to the starting welding point of another construction window 21, and welds the inner corner of the U-rib during the process of returning from the starting welding point of another construction window 21. The advantage of this is that the welding slag generated by welding falls behind the overhead welding vehicle 51, and the return welding can make the welding slag fall behind the travel direction of the overhead welding vehicle 51, which does not affect the travel of the overhead welding vehicle 51.

[0077] In addition, it is worth noting that, as Figure 10 As shown, due to the opening position of the construction window, the starting welding point S can be located further forward of another construction window, or even extend into another U-rib, so as to weld the overhead angle of the U-rib at the construction window. Further, the termination welding point T can also be at this time, and since the partitions at both ends of the construction window are cut, the overhead welding vehicle can enter the left U-rib through the lifting platform at this time, so as to weld the inner corner of the U-rib above the construction window with the lifting platform below. After completing the welding at the termination welding point T, the overhead welding vehicle can return to the lifting platform, and then perform subsequent operations.

[0078] That is, the opening of one construction window can connect the interiors of two U-ribs, and the overhead welding vehicle can travel in the two U-ribs during welding, and one construction section includes two construction windows, which actually connects three U-ribs. Thus, the overhead welding vehicle can travel in the three U-ribs with the assistance of the lifting platform and the temporary support, so as to completely weld the U-rib. However, in some other embodiments of the present application, when the construction window is opened on the U-rib at the end of the bridge, it can only extend into the U-rib inside the bridge in the direction of the bridge interior, which can cause the inner corner of the U-rib above the construction window to be unable to be welded, because the overhead welding vehicle cannot travel out of the end of the bridge. In this case, manual repair welding can be used to repair weld the inner corner of the U-rib above the construction window at the end of the bridge. The need for manual repair welding is only at the end of the bridge, which greatly increases the construction efficiency.

[0079] In some other embodiments of this application, a welding torch can also be installed on the overhead welding vehicle. After entering from a construction window 21, welding can be performed on an overhead angle along the longitudinal direction of the U-rib. After the welding of the overhead angle is completed, as the overhead welding vehicle 51 returns to the construction window 21 where it entered the U-rib, the welding torch can turn to another overhead angle and perform welding on the return trip. This allows for a larger range of motion for the welding torch.

[0080] Furthermore, in some embodiments of this application, such as Figure 5 and Figure 6 As shown, overhead welding car 51 ( Figure 5 (Outlined by dashed lines) The welding carriage 511 includes a welding cart 511 and a wire feed cart 512 connected to the rear of the welding cart 511 via a pipe 513. The wire feed cart 512 is used to feed welding wire to the welding cart 511. During overhead welding, the welding cart 511 and the wire feed cart 512 move synchronously. The front end of the welding cart 511 of the overhead welding cart 511 is equipped with a welding torch 514, which includes a welding torch nozzle 515 and a contact tip 516. Preferably, the contact tip 516 extends beyond the welding torch nozzle 515 by 5–15 mm. This distance can be adjusted according to the specific welding method, welding parameters, spatter size, U-rib angle, weld bead size, and the width of the U-rib 20, within a specific range of 5–15 mm. Setting the contact tip 516 to extend beyond the welding torch nozzle 515 by 5–15 mm can prevent welding spatter (high-temperature spatter particles are generated during gas shielded welding) from adhering to the nozzle. Prolonged welding would clog the contact tip, leading to short circuits and arc interruptions. Furthermore, to prevent the formation of serrated edges on both sides of the weld after welding, which would lead to stress dispersion, the welding speed of the overhead welding carriage 51 and the arc oscillation frequency of the welding torch should satisfy the following formula:

[0081] v = KfB

[0082] In the above formula, v represents the welding speed; K represents the overlap coefficient, ranging from 0.5 to 0.8, and this value is determined according to the weld formation requirements; f represents the oscillation frequency; and B represents the linear welding speed under the corresponding welding conditions. The weld width at that time, where w represents the swing amplitude in this formula, is determined based on the weld leg size requirements. In the preferred embodiment of the application, the oscillation frequency f is preferably 0.5Hz to 4Hz, the swing amplitude is preferably 0.5mm to 3mm, and the welding speed is preferably 200mm / min to 600mm / min; other parameters are preferably a welding wire diameter of 0.8mm, 1.0mm, or 1.2mm, a welding wire extension length of 15mm to 25mm, a shielding gas flow rate of 20 to 25L / min, and an angle between the welding torch and the top plate of 38° to 50° (see Appendix). Figure 7), welding current 80-220A, arc voltage 18-28V. The above parameters are set for the overhead welding vehicle, and the overhead welding vehicle travels in the U-rib and performs overhead welding on the inner corner of the U-rib on both sides.

[0083] After the welding operation in steps S4-1 to S4-4 is completed, the welding is finished, the overhead welding vehicle 51 is run onto the lifting platform 52 again, and the lifting platform 52 is lowered to the initial height, and the overhead welding vehicle 51 is taken out, S4-5. As described above, the overhead welding vehicle 51 performs welding on the inner corner of the U-rib when the overhead welding vehicle 51 travels back to the window through which the overhead welding vehicle 51 enters in the next window in a welding construction section, and when the welding is completed, the overhead welding vehicle 51 is usually located inside the U-rib, i.e., inside the partition 30, and therefore, the overhead welding vehicle 51 needs to be continuously run onto the lifting platform 52 by remote control, so as to take out the overhead welding vehicle 51.

[0084] In addition, when the overhead welding vehicle 51 runs to the construction window 21 on which the temporary support 53 is laid, the inner corner of the U-rib 20 above the construction window 21 can be overhead welded, and the overhead welding vehicle 51 will not fall due to the support of the temporary support 53. Moreover, the U-rib above the construction window 21 has a certain guiding effect on the running direction of the overhead welding vehicle 51, because the U-rib is reserved in the height direction during the opening of the construction window 21, and therefore, the overhead welding vehicle 51 will not deviate from the running direction.

[0085] Since the present application adopts the sectional welding method, the above embodiment is described by taking one welding construction section as an example, in which case, the lifting platform is arranged below one construction window in the welding construction section, and the temporary support is arranged below another construction window in the same welding construction section, so as to perform welding on one welding construction section. After the welding is completed, other welding construction sections are welded in turn.

[0086] Further, after the overhead welding of the inner corner of the U-rib in one welding construction section is completed, the U-rib 20 in the welding construction section in step S4 needs to be recovered and welded S5. Specifically, as shown in Figures 7 to 9 S5-1, i.e., the partition 30 on both sides of the construction window 21 is welded, and the welding gun enters the construction window 21 to perform single-sided fillet welding, and the welding size is greater than 6mm. Subsequently, the construction window 21 is welded S5-2, i.e., the repair welding at the construction window 21 is performed. Specifically, the window welding adopts carbon dioxide gas protection steel backing single-sided welding, and the welding seam has two layers and three passes: one pass of the base layer 61, and two passes of the surface layer (welding seams 62 and 63), as shown in Figure 9As shown, in some embodiments of this application, the window sealing welding may include the following steps: welding bevel preparation; metal pad spot welding fixation; construction window spot welding fixation; and welding of the butt joint of the U-rib at the construction window. The spot welding fixation of the construction window and the welding of the U-rib butt joint at the construction window actually refer to the restoration of the cut-off U-rib portion after the U-rib was cut according to the markings when the construction window was opened. In other words, the U-rib cut off during the construction window opening needs to be re-welded to its original position. After the partition and construction window are welded back together, a butt joint will form between the cut-off U-rib portion and the retained portion of the U-rib. Therefore, post-processing S5-3 is required at the window sealing weld. This post-processing can be surface grinding or stress relief treatment of the window sealing weld (i.e., the butt joint). This can prevent stress concentration at the butt joint, which could lead to the U-rib at the construction window becoming unstable and detaching.

[0087] In this article, it should be noted that the above step S5-1 actually includes, when the entire welding operation of the bridge is not completed, sealing the partitions at both ends of one of the construction windows in a welding construction section (i.e., the welding construction section that has been completed), sealing the construction window, and opening a new construction window at the other end of another U-rib corresponding to another construction window, and using the other construction window and the newly opened construction window as the next welding construction section.

[0088] In other words, when the internal corner welding of the bridge U-rib is not yet completed, and it is necessary to carry out construction operations on welding sections adjacent to the completed welding sections, it is only necessary to seal and weld the partitions at both ends of the construction window furthest from the section to be welded in the completed welding section, and then weld that construction window. In this way, the other construction window closer to the section to be welded can serve as a construction window for that section, and another construction window can be opened on the other side. This greatly improves construction efficiency. After all construction operations are completed, all unsealed construction windows can be sealed and welded together, thus completely restoring the U-rib.

[0089] Furthermore, the cutting of the U-ribs and partitions mentioned above in this application can be performed by flame cutting, plasma arc cutting, or laser cutting.

[0090] Further, in some embodiments of the present application, after the above-mentioned sealing window welding and welding seam processing of the construction window are completed, the method of the present application further comprises: painting S6 the outer surface of the sealing window welding of the construction window 21, i.e. after the welding seam processing, since the solder of the sealing window welding is exposed, it is easy to cause the oxidation of the solder and the surrounding material, resulting in falling off, therefore, the joint can be painted, such as antioxidant and the like, to avoid the oxidation of the solder.

[0091] At this point, the welding operation of the inner corner of the U rib in service is completed, the construction window of the above-mentioned U rib can be opened according to the welding construction section, and two are opened correspondingly in one group; wherein the two adjacent welding construction sections can share the construction window therebetween, which is sometimes used as the window for the entry of the overhead welding vehicle into the U rib, and sometimes used as the window for pushing out the sundries and placing the temporary support thereon. A plurality of construction windows can also be opened on the bridge, so that the inner corners of the U ribs in need of welding are simultaneously welded, greatly improving the welding efficiency. The practical application of the method of the present application will be illustrated by way of example 1.

[0092] Example 1

[0093] For the U rib inner corner welding of a domestic orthogonal steel structure bridge, the operation steps are as follows:

[0094] 1) The length of the construction window is positioned at 950 mm, the distance from the construction window to the upper side of the U rib is 120 mm, the U rib is marked according to the size and position of the construction window, the cutting is carried out along the marking line by using the plasma arc cutting method, and the cut U rib part is removed, so as to open the construction window for welding on the U rib of the orthogonal steel structure bridge;

[0095] 2) The partition plate in the U rib is cut and the cut partition plate is removed;

[0096] 3) The cut between the removed partition plate, the plate unit and the U rib is polished; the excess height of the butt welding seam of the plate unit and the metal backing plate in the U rib are polished; the area to be welded in the U rib is polished; and the inside of the U rib is cleaned by using the obstacle removing vehicle;

[0097] 4) placing the overhead welding vehicle on the lifting platform, placing the temporary support at another construction window of the same welding construction section, lifting the lifting platform to a height such that the overhead welding vehicle can smoothly enter the inside of the U rib, starting the overhead welding vehicle to drive along the longitudinal direction of the U rib to be repaired to the starting point of welding, then starting the welding procedure to make the overhead welding vehicle weld the inside corner of the U rib along the longitudinal direction of the U rib in the inside of the U rib during the return, after the welding is completed, the overhead welding vehicle is run onto the lifting platform again, and the lifting platform is lowered to the initial height, and the overhead welding vehicle is taken out, wherein the inside corner is overhead welded by MAG welding, and the welding material and parameters are as follows: the welding wire brand is H08Mn2SiA, the welding wire diameter is 1.2 mm, the protective gas is 80% Ar+20% O2, the gas flow is 25 L / min, the welding current is 220 A±10 A, the arc voltage is 21 V±1 V, the welding speed is 220 mm / min, the arc swing range is 2.5 mm, and the swing frequency is 1.3 Hz;

[0098] 5) sealing the partition plate in the U rib, sealing the construction window on the U rib, and post-processing the sealing welding position of the construction window; and

[0099] 6) coating the outside of the sealing welding position of the construction window.

[0100] According to the second aspect of the present application, a welding system is further provided for implementing the method for welding the inside corner of the U rib of the in-service steel structure bridge according to the preceding aspect, and the welding system comprises a lifting platform, a temporary support and an overhead welding vehicle. The lifting platform is used to send the overhead welding vehicle into the U rib through the construction window. The temporary support is used to support the driving of the overhead welding vehicle, and the temporary support is arranged at the construction window below which the lifting platform is not arranged. The temporary support can be provided with hooks or other devices at both ends, and can be hung at the edge of the construction window without falling during use. The overhead welding vehicle has been described in detail in the first aspect, and will not be described here again. In some embodiments of the present application, the temporary support can be a detachable track which can further guide the driving direction of the overhead welding vehicle to make it drive stably by matching the U rib part reserved above the construction window.

[0101] Further, the welding system can further comprise a metal cutting device, a sealing welding device and a coating device. The metal cutting device is used to cut the U rib and the partition plate to open the construction window and remove the partition plate. The sealing welding device is used to weld the opened partition plate and the U rib to restore the structure of the U rib. The coating device is used to coat the sealing welding position of the construction window after the welding construction is completed.

[0102] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the application and their practical application to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present application, and various alternatives and modifications thereto, and it is intended that the scope of the application should be defined by the claims appended hereto and their equivalents.

[0103] It can be understood that the above embodiments are merely exemplary embodiments adopted for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and these modifications and changes are also considered to be within the scope of protection of the present application.

Claims

1. A method of welding an inner corner of a U rib of a welded steel bridge in service, both ends of the U rib being provided with a bulkhead, characterized in that, The method comprises the following steps: S1, opening a welding construction section: opening a construction window for welding on the U rib in service, the opening position of the construction window is between two bulkheads on both sides of the welding seam of the U rib, and is located on both sides of the butt welding seam of the plate unit to which the U rib is welded, and each adjacent two construction windows are a welding construction section; S2, cutting the bulkheads on both sides of the construction window and taking out the cut bulkheads; S3, polishing the cut boundaries of the plate unit and U rib in a construction section, and cleaning the inside of the U rib of the welding construction section; S4, upwelding the inner corner of the U rib in the welding construction section in step S3; and S5, restoring welding of the U rib in the welding construction section in step S4, wherein The step S4 comprises the following steps: S4-1, placing an upwelding vehicle for upwelding the inner corner of the U rib on a lifting platform, and the lifting platform is arranged on the ground below one construction window of the welding construction section; S4-2, arranging a temporary support at the other construction window of the welding construction section, and the temporary support is a detachable track; S4-3, lifting the lifting platform to a height such that the upwelding vehicle can smoothly enter the inside of the U rib; S4-4, starting the upwelding vehicle to upweld the inner corner of the U rib in the longitudinal direction of the U rib inside the U rib; And S4-5, after welding, running the upwelding vehicle to the lifting platform again, and lowering the lifting platform to the initial height, taking out the upwelding vehicle, and wherein The upwelding vehicle is provided with a welding gun, the welding gun comprises a welding gun nozzle and a conductive nozzle, the conductive nozzle extends out of the welding gun nozzle by a distance of 5-15 mm, and the welding speed of the upwelding vehicle and the arc swing frequency of the welding gun satisfy the following formula: v=KfB where v represents the welding speed; K represents the overlap coefficient; f represents the oscillation frequency; B represents the weld width when the linear welding speed is v = 0.5Bf 2. The method of welding interior corners of U-ribs of a steel bridge in service according to claim 1, characterized in that, The longitudinal length of the construction window is less than the distance between the two bulkheads by 50-100 mm, and the distance from the construction window to the lower surface of the plate unit is greater than 80 mm, and wherein the step S1 comprises the following steps: S1-1, marking the U rib according to the size and position of the construction window; and S1-2, cutting along the line marked in step S1-1, and removing the cut U rib part to form a construction window.

3. The method of welding interior corners of U-ribs of a steel bridge in service according to claim 1, characterized in that, The polishing of the plate unit and U rib in step S3 comprises: S3-1, polishing the cut between the removed bulkhead and the plate unit and the U rib; S3-2, polishing the excess height of the butt welding seam of the plate unit and the metal backing plate inside the U rib; and S3-3, polishing the to-be-welded area inside the U rib.

4. The method of welding interior corners of U-ribs of a steel bridge in service according to claim 1, characterized in that, The step S5 comprises the following steps: S5-1, sealing the bulkhead inside the U rib, and sealing the construction window, and S5-2, post-processing the sealing welding.

5. The method of welding interior corners of U-ribs of a steel bridge in service according to claim 4, characterized in that, The step S5-1 further comprises, when all welding operations of the bridge are not completed, sealing the partition plates at both ends of one of the construction windows in one of the welding construction sections, sealing-window welding of the construction window, and opening a new construction window at the other end of the other U rib corresponding to the other construction window, and taking the other construction window and the newly opened construction window as the next welding construction section.

6. The method of welding interior corners of U-ribs of a steel bridge in service according to any one of claims 1 to 5, characterized in that, The method further comprises: S6, painting the outer surface of the sealing-window welded portion of the construction window.

7. A welding system characterized by, The welding system is used to implement the method of welding the inner corner of the U rib of the steel structure bridge in service according to any one of claims 1-6, and the welding system comprises a lifting platform, a temporary support and an overhead welding vehicle; The lifting platform is arranged on the ground below one of the construction windows of the welding construction section, and is used to send the overhead welding vehicle into the U rib through the construction window; The temporary support is used to support the travel of the overhead welding vehicle, and the temporary support is arranged at the construction window below which the lifting platform is not arranged.

8. The welding system of claim 7, wherein: The temporary support is a detachable track.

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